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fljmayer writes "In this experiment, researchers in Australia and Japan were able to transfer quantum information from one place to another without having to physically move it. It was destroyed in one place and instantly resurrected in another, 'alive' again and unchanged. This is a major advance, as previous teleportation experiments were either very slow or caused some information to be lost."

If they really mean 'instantaneously', then it's a pretty major upset in our current knowledge of physics. If they mean 'at a speed less than or equal to the speed of light in a vacuum in a straight line', then it's still useful (maximum 42ms latency anywhere in the world), but has been thought to be possible for a while. If it really is instantaneous then there are going to be all sorts of fun causality-violating experiments to try...

Intentional misspelling is intentional. My comment is about as profound as the previous, that governments would just disappear quantum physicists for effectively doing "science". I'm not entirely sure I'd see the point. It would just produce a technological dark-age (relatively to the potential of having mainstream quantum machines/computers eventually). The two posts, you see, are entangled. One is spun into silliness in the form of conspiracy, the other is spun in the opposite direction as a Yo Dawg

In one instance, you're making sure that felines are in their appropriate (to you) places. In the other, you're making sure that "you [who] like[s] conspiracy theories" is in the appropriate place. I think most would agree that managing software developers is more akin to the former than the latter (although there is a significant overlap in attraction to conspiracy theories, as there is attraction to software development, generally due to the edge cases).

That's because "spooky action at a distance" is really called Quantum Entanglement...which IS in the article.

FTFA: "The team employed a mind-boggling set of quantum manipulation techniques to achieve this, including squeezing, photon subtraction, entanglement and homodyne detection. The photo above depicts their device, nicknamed the Teleporter, in the lab of Akira Furusawa at

Transferring information faster than the speed of light through the use of quantum entanglement is impossible. Only through the use of a second, traditionally light-speed-bound communication channel one make any use of the oddness that is quantum entanglement.

That said, it might still have practical uses, but instantaneous communication to the other side of the galaxy is not one of them.

Although I figured using it as a network interconnect across the planet, say EU to US would be a good start, of course depending how quick you can flip that bit as to whether it's even feasible vs under sea cables. Though saying that I figure it's far more complex than merely using it as an overcomplicated cable. No doubt thinking of traditional uses for quantum processing systems is too simple, but I'm not a quantum physicist so I'm a bit stuck there. The engineer part of me says "Right, now what? Let'

A scientific theory is not infallible. Although, from what we've observed, it may be highly unlikely that anything could violate it, it is not necessarily impossible. It takes but a single example to disprove it, no matter how unlikely that is.

That's technically true, I suppose, but it doesn't seem like a productive way to do research - essentially your only chance of success is if everything we know about physics is wrong.

- essentially your only chance of success is if everything we know about physics is wrong.

It wouldn't be the first time.

That said, I truly doubt that most of the fundamentals are wrong at this point, but they may be. I wouldn't be terribly shocked if something we held as a law was completely demolished in my lifetime, I would be shocked if this didn't happen actually.

My understanding is that even quantum entanglement is still limited by the speed of light. I think the main advantage of quantum entanglement vs. radio communication is greater privacy. Also, I'm not completley positive on this, but I think that, whereas a limited number of users can 'share' a bit of the RF spectrum, as long as you have more entangled particle pairs, you have essentially unlimited bandwidth.

and I really think this is quite intuitive - that cats can't be both dead and alive at the same - why is this so hard for people (and especially popular science writers)?

Which brings up a converse point; why should physics be intuitive? We evolved to understand a certain scale, this outside this scale are going to be very strange. Relativity isn't really that intuitive, try to explain all the strange side-effects of that theory to lay people. On smaller scales, quantum mechanics are just as intuitive has relativity... meaning, completely nonsensical to our normal existence. Time does not dilate, objects don't elongate or contract based on relative speed per frame of re

When it says information passed between the two points is information, does it mean it changes energy states? Because I think there would be a lot of devices that could be engineered with an offsite energy source instead of having a fuel tank.

It's not really quite clear what the breakthrough is here. But I'm fairly certain it doesn't involve a group velocity (i.e. information transmission) greater than c.

You're right, it isn't. This article makes me sick. If people take shit like this seriously they can't be blamed for not being able to differentiate real science from quantum woo [rationalwiki.org].

It's better to just ignore than try to correct it.

Teleportation [wikipedia.org] is a real phenomenon, albeit a bit old. This is not their breakthrough. The breakthrough is doing it with a cat state (the name is a reference to Schrödinger's cat; this kind of state was inspired in it). These states are usually very fragile, and strongly entangled, hence the interest.

Also other breakthrough is doing it with the measurement of the number of photons and position. This is a promising technique, that I am personally working with at the moment to test Bell inequalities, because of its high resistance to noise. But I don't think it is very exciting to the general public...

Ah, but your/. crowd is not in that category. Maybe all of us/.'ers are not very interested in this subject: that does not mean a substantial percentage of us are not.

My original intent was to post a snarky/sarcastic comment with the title of "Beam me up, Scotty", followed with a comment about Teleporter/Transporter tech finally advancing a small step in the 'right/correct' direction to make it happen.

Don't give up on us 'laymen', and arm-chair physicists. Maybe we can't join the ranks with our PHD's, bu

This is what bothered me about it, too. The words "destroyed in one place and instantly resurrected in another" clearly imply superluminal information transfer. And it gave me pause, because I am familiar with the theory that information cannot be transferred faster than light. Not 100% convinced by it, but familiar with it. I thought it was a good enough approximation, anyhow, for the present time.

So then I read that quantum experimenters -- who are clearly on the cutting-edge of physics -- are now "ins

Yes, it's in the details,I haven't read this article, but I assume it's similar to other methods than seem to invoke FTL.

You can't be sure what state you have before you transfer it, and if you do measure it, it changes the state. Therefore, when you teleport the current state, the receiver can see what state it's in, let's say 0 or 1. But since the sender didn't know if it was a 0 or a 1, the information is useless.

Personally I think spooky action at a distance isn't spooky at all. Consider the tim

The actual spookiness is in the details, like what if I now measure it's spin with respect to a different axis, the classical and quantum results differ then, but I cannot think of any practical application this provides us.

Basically, the rate of correlation when measuring entangled things is a function of the orientations of the detectors. The only way to explain that is: 1> Assume that the universe is deterministic, so the entire future state of the system is known at the time of the event that creates the entanglement; 2> Assume that a change made to one member of an entangled pair have an instant effect across any distance on the other member of that pair.

Since entanglement and randomness are inextricably linked here, there's no way to use the effect to either foresee the future or communicate faster than light (and by extension, change the past). So you're right that there's no practical application for it.

It just raises some extremely thought-provoking questions about the nature of our reality.

With the classic double-slit experiment, the argument is that the quantum particle goes through both slits because of the way it interferes with itself at the detector (interference pattern). But can we do something similar with quantum teleportation: have my friends in Japan and Australia mail the boxes back unopened, merge the contents of the two boxes and show that the single resulting ball has been to both Japan and Australia?

Well, if the boxes were mailed back unopened and somehow merged back toget

Basically, the rate of correlation when measuring entangled things is a function of the orientations of the detectors.

OK, so suppose I have two boxes and one ball. I put the ball in one of the boxes at random and mail one box to a friend in Australia and the other box to a friend in Japan. Then, when my friend in Japan opens his box, he "instantly" knows whether the ball is in the box in Australia. The information about the Australian box has instantly teleported from Australia to Japan, so to speak.

But what you seem to be saying is that if the box in Japan is opened from the top then there is always exactly one ball - which is either in the Japan box or the Australia box. But that if the box in Japan is opened from the side then there might be zero, one, or even two balls - neither box could contain a ball - or both boxes could each contain a ball.

With the classic double-slit experiment, the argument is that the quantum particle goes through both slits because of the way it interferes with itself at the detector (interference pattern). But can we do something similar with quantum teleportation: have my friends in Japan and Australia mail the boxes back unopened, merge the contents of the two boxes and show that the single resulting ball has been to both Japan and Australia?

What if you have three boxes, you open one, then Monty Hall opens another one?

Physicists will say, how could the other electron possibly know this, instantly

Why would they assume that the electrons are separated? Because we perceive them that way?

Isn't it easier to assume that they're not separate entities and that we just don't know how the universe is put together than to assume that we understand the universe and there's a 'magical' force communicating across infinite distance?

Isn't it easier to assume that they're not separate entities and that we just don't know how the universe is put together [...]

Sure, you can do that. But if you stop there, you'll know nothing; so we have to go on and keep trying to understand.

[...] than to assume that we understand the universe and there's a 'magical' force communicating across infinite distance?

The thing is, that's not what physicists are saying -- that's just a bastardized explanation used when you can't make someone take a few classes that require quite a bit of math to understand[1]. In fact, most physicists, if pressed, will admit no one knows what is really going on. For example, there's a famous quote by Richard Feynman: "I think I can safely say that nobody understands quantum mechanics".

What physicists do know is a theory that allows us to very successfully predict the outcome of many experiments and understand many phenomena better than any classical (completely understood) theory; and certainly better than if we just give up and assume that "we just don't know how the universe is put together", as you suggest. The amazing thing is that this theory can explain every phenomena we have ever seen (except gravity) and predict the outcome of any experiment we can perform.

The problem is, this theory (quantum mechanics) just doesn't make clear what's really going on. There are many tentative interpretations [wikipedia.org] that are consistent with the theory and the experimental results, each of them having at least one very strange feature (instant collapse of the wavefunction -- which I guess would be the "magical force" you mentioned --, or parallel universes, etc.) that fails to convince most people, including physicists.

Most (all?) physicists working with quantum physics know this very well. But since "what's really going on" is not very important to do research, they don't think about it that much. What they really want is to predict more stuff and come up with new ways to use the strange behavior we see for our advantage.

[1] By the way: there's an excellent very basic course on YouTube about quantum entanglement: http://www.youtube.com/view_play_list?p=A27CEA1B8B27EB67 [youtube.com]. It only requires high-school algebra (including complex numbers, I don't know it everyone takes that in high school), and patience to follow it through. I guarantee you that you'll end up having a good idea of how this quantum stuff works (at a very basic level) without any mention of magical forces communicating across infinite distances.

Take a source of entangled photons.. It could emit one photon at 0 polarised (for vertically polarised), and one at 90 for horizontally polarised, in a continuos random stream of.... lets also imagine that this set of emitted photons are a bit stream. H for 0, and V for 90. It could look like this

Personally I think spooky action at a distance isn't spooky at all. Consider the time-honored classic of two electrons in a correlated state being shot out of some device. Assume they are entangled in such a way that when you measure one to be up, you instantly know the other is down. Physicists will say, how could the other electron possibly know this, instantly. But a very simple explanation is that the device always shoots 1 up, 1 down. Sure you don't know if it's up or down until you measure it, but that doesn't make it spooky at all.

Except that other experiments show it doesn't work that way. It's not "you don't know if it's up or down until you measure it", it's you know it's in a superposition state of up and down that "decide" to be only up or only down only when you (or a detector) look at it.

How do you explain that when you change the spin of one you change the spin direction of the other aswell?

Two words: Transactional Interpretation.

The only spooky thing about 'spooky action at a distance' is that people think it's spooky. It's just a consequence of using non-relativistic quantum mechanics; you shouldn't be surprised that non-relativistic physics allows things to travel faster than light.

A standing wave formed by future waves and waves from the past still seems a little spooky to me. However it seems there is still quite a bit of debate as to whether this accurately describes the situation. Thanks for the link.

What you are suggesting sounds like an ansible. This is a science fiction FTL communication device invented by Orson Scott Card. It's based on the idea of a trapped subatomic particle that has been split in two, while the resulting pair of particles remain permanently linked such that any change made to one is reflected instantly in the other no matter how much spacial distance separates them.

Quantum entanglement can be thought of as working like that, except that as soon as one of the split particles in

Quantum entanglement can be thought of as working like that, except that as soon as one of the split particles interacts with anything else at all in any way and the resulting change is "transferred" to the paired particle, that entanglement is broken.

This is not correct. You can *measure* some property and then you know the value of the other particle and entanglement is broken. You can't force the result of the measurement. In other words the only "spooky" action at a distance is the "instant" entanglement braking. And the guy with the other particle can't even observe that either. He/She still needed to make the measurement to determine the state of his/her particle.

This is a quote from user holmstar that explains is very well. (msg id #27448983 bu

Thanks for that! In reading your comment, before I saw the link, I was already picturing that goofy bald-headed actor from Just Shoot Me, as I'd seen that Outer Limits episode many years back. Really disturbing... (The moral dilemma, that is, not the goofiness or hair loss.)

Isn't there some law of physics that says information can not be transmitted faster than the speed of light?

Yes. The headline is incorrect. The experiment 'teleported' the quantum state of photons (but not the photons themselves, that is almost certainly impossible, or at least, grossly impractical) in a way that was much faster than previous experiments. But still slower than the speed of light.

To be fair to the headline, the text of the article mentions that the state was transmitted instantly, which implies speeds faster than light.

As odd as it sounds, there's not actually any difference between teleporting "only" the quantum state of the photons and teleporting the photons themselves -- provide the state you're teleporting is the entire state of the photon. Quantum mechanical particles are entirely defined by their state; beyond that state, they're all the same. (Of course, this is counterintuitive.)

Still, while the state change technically is propagated instantaneously (a pair of entangled photons are sharing a single state, so chan

As a non-physicist, I have yet to hear a good explanation for any useful means of turning faster-than-light travel into time travel, and every explanation I have heard sounds pretty absurd.

If an a cause triggers an effect somewhere else in a faster-than-light fashion, sure, an outside observer in some frame of reference might be able to observe it occurring before the cause. This happens any time that the outside observer is closer to the effect than to the cause. However, at no point does that observer o

If an a cause triggers an effect somewhere else in a faster-than-light fashion, sure, an outside observer in some frame of reference might be able to observe it occurring before the cause. This happens any time that the outside observer is closer to the effect than to the cause. However, at no point does that observer observe the effect before the cause occurs. If that observer is, for example, five light years away from the effect and ten light years away from the cause, then the observer still observes the effect five years after the cause occurred.

I'm not a physicist either, but let me see if I can explain this.

Suppose you have three points arranged along a line, say A, B and C, so that A is e.g. 10 light years away from C and B is half way between them, and at the starting time they're all stationary with respect to one another.

Now suppose Alice at point A sets off at the speed of light for point C. An observer at point C will observe that A leaves and arrives at the same time (or almost the same time, if Alice is traveling slightly slower than the